Abstract: In this paper,a method to detect live Salmonella cells was developed based on propidium monoazide( PMA) and dd PCR.The result showed that PMA could not inhibit the DNA PCR amplification of 108 CFU / m L dead Salmonella cells,while the combination of sodium deoxycholate( SD) and 40.0 μg / m L PMA could do it. The maximum concentration against DNA amplification from live Salmonella cells was 40.0 μg / m L.Only live Salmonella cells were detected by PMA- dd PCR even in the existence of dead Salmonella cells,and the detection limit was8.0 copy /20 μL. PMA- dd PCR could detect 102 CFU / m L Salmonella cells in the polutted sample made by manual work. Furthermore,PMA- dd PCR showed better specificity,accuracy and stability.